Shape Group Transform Position Property

Hello Community,

Please see my screenshot below, I can't figure out how the position property in a group transform is derived.  I understand the relationship between the composition coords and the layer coords re. anchor points and position; but the group position property is confusing me; I can't relate its coords to the layer or the comp.  I've searched for info but to no avail.  Please adivse or point me in the right direction.  Thanks in advance for your help!